A cumulative average recalculates a data set's average as new data is added. During the recalculation all data contained in the data set is included in the average. In Microsoft Excel your spreadsheet should allow the inclusion of new data to a series of data points and have the average updated to reflect the new information. The resulting chart needs to automatically update to reflect the new average. Fortunately, Excel automates most of these tasks as long as you set up your spreadsheet correctly.

1

Open Microsoft Excel.

2

Enter you data down column A.

3

Enter "=AVERAGE(A:A)" in cell B1. This configuration looks for all data points in column A so when you add data to the column, it is included in the average.

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4

Click cell B1 to select it.

5

Click the "Insert" tab.

6

Click either "Column" or "Bar" from the Charts group and select the top left chart type. The only difference between Column and Bar charts is their vertical or horizontal orientation, respectively. The cumulative average chart is created on the same page and will automatically update as you add more data.